EPIDEMIOLOGY AND MANAGEMENT OF CANOLA DISEASES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1021071
• Project Start Date: Nov 12, 2019
• Project End Date: Sep 30, 2024
• Program Code: [(N/A)]- (N/A)

Recipient Organization
NORTH DAKOTA STATE UNIV
1310 BOLLEY DR
FARGO,ND 58105-5750

Performing Department
Plant Pathology

Non Technical Summary
Three important diseases affect canola production in North Dakota. These diseases, blackleg, clubroot, and Sclerotinia stem rot can severely reduce yields if left unattended. New races of blackleg are increasing in prevalence and can infect otherwise resistant cultivars. We intend to develop a warning system that will alert farmers when spores of the blackleg pathogen are in the air to better time their fungicide applications. Clubroot was recently discovered in North Dakota and until the summer of 2018, approximately 30 fields, all within Cavalier County, had tested positive for the disease. This project intends to identify sources of resistance and genetic markers associated with it that can be used to produce cultivars resistant to this dangerous disease. Sclerotinia stem rot, like blackleg, is endemic in canola producing areas of North Dakota. For the disease to occur, sclerotia needs to produce apothecia and ascospores released from apothecia need to cause infection on flowers and leaves before it enters the stems. Yield reductions occur when the pathogen enters the stem and branches of plants. A disease-warning system produced by our program and based on air temperature and precipitation prevalent during the second half of June and during July, is currently in use by farmers in our region. We intend to improve the accuracy of the current warning system by adding models that estimate probability of apothecia production and of leaf lesion production. It is expected that adding these components will contribute to the overall accuracy of the model and will reduce the number of unnecessary fungicide applications aimed at controlling this disease.The information generated through this project will be shared with farmers, extension county agents, and other agricultural professionals that serve the canola industry of our region, through a variety of educational activities including field days, canola-specific winter meetings, professional meetings, and manuscripts for peer-reviewed journals and extension materials. Research results also will be made available to farmers through the Northern Canola Growers Association website and the Canola Doctor, a cell phone application developed by our program. The activities outlined in this project will improve sustainability of canola production in the region.

Animal Health Component

100%

Research Effort Categories

Basic

0%

Applied

100%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
212	1848	1160	80%
202	1848	1081	10%
205	1848	1060	10%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 205 - Plant Management Systems; 202 - Plant Genetic Resources;

Subject Of Investigation
1848 - Canola;

Field Of Science
1060 - Biology (whole systems); 1160 - Pathology; 1081 - Breeding;

Keywords

canola

clubroot

blackleg

sclerotinia stem rot

survey

races

genetic markers

Goals / Objectives
The goal of this project is to ensure the continued productivity and sustainability of the canola industry in North Dakota.This goal will be achieved through the development of more effective disease management practices and more disease-resistant germplasm. Specific objectives of this project are:Characterize the epidemiology of important diseases that affect canola production in North DakotaIdentify and characterize host-resistance against diseases that affect canola production in North Dakota

Project Methods
Characterization of the prevalence of avirulence genes in L. maculans (AvrLm) populations and identification of specific resistance genes: Detection of some blackleg avirulence genes will be achieved using greenhouse inoculation of a set of differential lines while other genes will be detected using polymerase chain reaction (PCR) assays with AvrLm-specific primers. Blackleg races carry specific combinations of avirulence genes and the resulting interaction between a race and a plant will allow us to infer the presence of resistance genes in that plant. Replicated inoculation trials in greenhouse will be used to assess the reaction of plant materials at the seedling stage to specific races. Reaction to inoculations will be quantified using a 0-9 severity scale. Presence of specific resistance genes will be inferred.Characterization of the reaction of commercial canola cultivars to L. maculans: Procedures outlined above will be used to evaluate the reaction of commercially available hybrids to the most common races. The information generated will help implement a labeling system that will be made available to growers, so they can use a hybrid rotation that reduces the selection pressure exerted on the pathogen. Development of a blackleg warning-system and improvement of the SSR-warning system: Volumetric spore samplers will be deployed at multiple locations between early May and the end of June during the 2019-2021 period to monitor presence of blackleg spores. Weather data for the sampling periods will be collected from NDAWN weather stations closest to each location. Logistic regression analysis will be used to develop models that associate weather patterns to peaks of spore release. Models will be validated using independent data sets and field trials. To improve the current Sclerotinia stem rot (SSR) warning system, a carpogenic germination model for Sclerotinia sclerotiorum, developed earlier by our program, will be validated by deploying three groups of 50 sclerotia each in a field at each of five locations. This validation study will be conducted for two years. Once validated, the model will be incorporated into the warning system. In addition, a model that estimates probability of SSR lesion development as affected by leaf wetness duration and air temperature will be validated in the summers of 2019-2021 at multiple locations. Predictions from the model using NDAWN weather data will be compared to field observations. After validation, the models will be incorporated to the current warning system.Identification of sources of resistance against clubroot and QTL detection: Approximately 418 B. napus plant introduction materials will be evaluated for their reaction to North Dakota isolates of clubroot in greenhouse conditions. The accessions will be evaluated in field and greenhouse trials using a randomized complete block design with three replications. Disease severity will be evaluated 45 days after planting using a standard clubroot severity scale. Data will be analyzed using non-parametric statistics. This study will be conducted twice. Genome-wide association mapping analysis will be used to identify markers associated with resistance to clubroot. The 20% most resistant accessions will be evaluated again, and the most resistant accessions selected for use in breeding programs.Identification of markers associated with resistance to blackleg: Doubled-haploid mapping populations will be developed from crosses between cv. Topas and three resistant plant introduction materials recently identified in our program. Cultivar Topas is selected for these crosses because it is very amenable for doubled haploid production and does not have known blackleg-resistant genes. Single-seed descent will be used as backup option to develop these populations. Mapping populations will be evaluated for their reaction to common ND races of blackleg. Quantitative trait loci identification will be performed using standard QTL mapping software and procedures.Identification of sources of resistance against S. sclerotiorum and QTL detection: Doubled-haploid mapping populations will be developed from crosses between S. sclerotiorum-resistant B. napus plant introductions 169080, 436554 and 458940 and cultivar Topas. Single-seed descent will be used as backup procedure to develop the mapping populations. At flowering, plants will be inoculated using the petiole inoculation technique in replicated trials with at least five plants per replication and four replications per trial. Genomic DNA will be extracted from these plants along with that of the parental lines and analyzed for SNP markers. The QTL associated with SSR resistance will be detected following standard procedures.Evaluation of breeding materials: The NDSU canola pathology program will continue working in close collaboration with the NDSU canola breeding program, to evaluate elite breeding lines under greenhouse and/or field conditions for their reaction to the most important diseases affecting canola production in the region.

Progress 11/12/19 to 09/30/20

Outputs
Target Audience:Research results were presented to two types of audiences: 1) the scientific community working on canola production problems: this audience was addressed twice in thereporting period using posters and verbal presentations as well as through a peer-reviewed manuscript. 2)canola growers and stakeholders: research results were presented to these audiences as an onlineoral presentation. Changes/Problems:The Covid-19 pandemic prevented us from establishing field trials and delayed production of mapping populations. Also, one PhD student graduated in 2020 and has left the program. We are currently recruiting a graduate student to continue the work of the graduate. What opportunities for training and professional development has the project provided?One doctoral graduate student finished her program and graduated in December 2020. Another doctoral student continues his research on clubroot. Results have been presented to an audience of 40 North Dakota famers and industry representatives. Also, results have been included in extension bulletins and have been presented by the extension service through other media (radio interviews and internet websites). Also, research results were presented to the scientific community at a national professional meeting. Worldwide audiences will be reached through two peer-reviewed manuscripts published in prestigious research journals. How have the results been disseminated to communities of interest?We have two main audiences, farmers that produce canola and scientists that conduct research on canola diseases. Farmers have been presented with up-to-date information on disease management and the research conducted by this project through online meetings. Also, research results have been included in four extension bulletins and have been presented by the extension service through other media (radio interviews and internet websites). Research results have been presented to the scientific community through articles published in refereed journals and through presentations at national professional meetings. What do you plan to do during the next reporting period to accomplish the goals?Sclerotinia stem rot: One biparental mapping population will be developed in 2021. This population will be evaluated to detect quantitative trait loci associated with resistance to SSR and to produce additional resistant lines. Transference of the resistance present in two other sources will start in 2021. Blackleg: A biparental mapping population will be developed from the cross of lines with resistance to SSR and to blackleg. Clubroot: Screening for detection of sources of resistance will continue in the coming year.

Impacts
What was accomplished under these goals? Three diseases affect canola production in North Dakota. They are, Sclerotinia stem rot (SSR) , caused by Sclerotinia sclerotiorum; blackleg, caused by Leptosphaeria maculans; and clubroot, caused by Plasmodiophora brassicae. SSR reduces yields by an average of 0.5% for every percent unit of incidence and is currently managed through fungicide applications. A fungicide application costs approximately $20-25 per acre. If 30% of fields are sprayed every year for control of SSR, this would represent a production cost of US$9-11 million. If the sources of resistance identified through this project are introduced into 10% of the area planted to canola, farmers could save more than US$3 million dollars annually in fungicide applications for SSR management. Blackleg is resurging because commercial cultivars are susceptible to new L. maculans races identified by this program earlier. Yield losses of up to 50% have been reported in the region. Disease surveys revealed that during the past four years, approximately 10% of fields experienced yield losses due to this disease with an estimated economic loss of US$9.6 million per year. Fungicides are still not widely used to manage this disease. If only 10% of the area dedicated to canola is treated with fungicides, that would represent an average increment of $20 per acre in production costs or approximately $3 million. If the sources of resistance identified through this project are used in 10% of the area planted to canola, farmers could save US$3 million annually in unnecessary fungicide applications. A third disease, clubroot, was discovered in the state in 2013 and still is limited to the northeast region of the state. This disease has greater damaging potential than the first two. The causal agent of this disease can survive in the soil in the absence of canola plants for more than 10 years and once established in a field could render it unsuitable for canola production. 1. Characterizing the epidemiology of important diseases that affect canola production in NorthDakota Sclerotinia stem rot epidemiology: A study that evaluated the influence of temperature and leaf wetness duration on development of SSR was completed and a logistic regression model was developed. The model will be used to improve the existing disease-warning program for SSR in the coming growing season. No major activites were conducted to study the epidemiology of blackleg or clubroot during thisreporting period. 2. Identifying and characterizing host resistance against diseases that affect canola production in North Dakota Resistance against blackleg: Doubled haploid resistant lines were developed from two sources of resistance previously identified by our program. These lines are being used to developbiparental mapping populations that will allow us to identify quantitative trait loci associated with resistance to blackleg. Resistance to Sclerotinia stem rot: Two doubled haploid mapping populations derived from resistant plant introductions 436554 and NEP63 were developed and evaluated. Resistant lines as well as 19 quantitative trait loci associated with resistance to this disease were identified. Resistance to clubroot: One hundred and twenty plant introduction germplasms were evaluated for their reaction to clubroot in field trials during 2019. Reaction of these lines is being verified and crosses will be made in early 2021.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Chittem, K., R., W. R. Yajima, R. S. Goswami, L. E. del R�o Mendoza. 2020. Transcriptome analysis of the plant pathogen Sclerotinia sclerotiorum interaction with resistant and susceptible canola (Brassica napus) lines. PLoS ONE 15(3): e0229844. doi.org/10.1371/journal.pone.0229844.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Shahoveisi, F., and L. E. del R�o Mendoza. 2020. Effect of wetness duration and incubation temperature on development of ascosporic infections by Sclerotinia sclerotiorum. Plant Dis. 104:1817-1823. doi.org/10.1094/PDIS-06-19-1304-RE.
• Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Shahoveisi, F. 2020. Characterization of genetic resistance to Sclerotinia sclerotiorum and epidemiology of the disease in Brassica napus L. PhD dissertation. North Dakota State University, Fargo, ND. 153 p.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Chittem, K., S. G. C. Upadhaya, and L. del R�o Mendoza. 2020. Characterization S. sclerotiorum isocitrate lyase gene in pathogenicity/virulence on canola. 18th National Sclerotinia Initiative Meeting, Jan. 22-23, 2020. Fargo, ND. Abstract pp. 8.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Roy, J., L. del R�o Mendoza, and M. Rahman. 2020. Genome-wide association study for Sclerotinia stem rot resistance in Brassica napus L. 18th National Sclerotinia Initiative Meeting, Jan. 22-23, 2020. Fargo, ND. Abstract pp. 14.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Shahoveisi, F., A. Oladzad, L. E. del R�o Mendoza, K. Chittem, S. Ruud, S. Hosseinirad, and B. Rissato. 2020. Identification of genomic regions associated with resistance to Sclerotinia stem rot in a Brassica napus doubled haploid population. 18th National Sclerotinia Initiative Meeting, Jan. 22-23, 2020. Fargo, ND. Abstract pp. 17.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Underwood, W., M. Overlandeer, and L. del Rio. 2020. WRKY transcription factors influencing levels of resistance to Sclerotinia in Arabidopsis thaliana. 18th National Sclerotinia Initiative Meeting, Jan. 22-23, 2020. Fargo, ND. Abstract pp. 25.
• Type: Other Status: Published Year Published: 2020 Citation: Markell, S., F. Shahoveisi, and L. del R�o. 2020. Using the canola risk map and risk calculator for white mold. In: Crop and Pest Report No 10. July 2, 2020. NDSU Online Extension Bulletin 17-18 pp.
• Type: Other Status: Published Year Published: 2020 Citation: Shahoveisi, F., S. Markell, and L. E. del R�o Mendoza. 2020. Blackleg of canola. NDSU Extension Service Bulletin PP-1988.
• Type: Other Status: Published Year Published: 2020 Citation: Shahoveisi, F., S. Markell, H. Kandel, and L. E. del R�o Mendoza. 2020. Canola diseases: Sclerotinia stem rot of. NDSU Extension Bull. PP-1989.
• Type: Other Status: Published Year Published: 2020 Citation: Smith, M., A. Chirumamilla, L. Berg, V. Chapara, F. Shahoveisi, L. E. Del Rio Mendoza, and S. Markell. 2020 Canola diseases: Clubroot. NDSU Extension Bull. PP-1998.